This invention relates to an outboard motor and more particularly to an improved lubricating system for an outboard motor.
As is well known, most outboard motors employ as their power plants, two-cycle internal combustion engines. One reason why a four-cycle engine is not normally employed in connection with outboard motors is the difficulty in providing an adequate lubricant sump with such motors. As a somewhat related problem, when a four-cycle engine is employed with a separate lubricating sump, problems can arise due to the fact that the motor is frequently inclined from its normal running position. That is, the motor may be tilted up when not in use or may be carried or laid on its side when not attached to a watercraft. When the motor is oriented in such extreme conditions, the oil is likely to flow back from the sump into the internal components of the engine and can cause damage. For example, the oil may flow back into the crank chamber of the engine or into the camshaft chamber where it can eventually leak into the combustion chambers past either the valves or the pistons. As a result, upon restarting of the engine, there can be considerable damage and furthermore it can cause pollution, particularly if the oil again drains back out of the engine through its exhaust system.
It is, therefore, a principal object of this invention to provide an improved outboard motor construction.
It is another object of this invention to provide an outboard motor having an improved lubricant sump arrangement that prevents draining back of the oil from the sump to the engine when the motor is in other than a normal running condition.
It is yet a further object of this invention to provide an improved four-cycle engine and lubricant sump therefor that prevents oil from returning into the engine from the sump when the engine is other than in its normal condition.